Heretofore, it has been well known in the railroad industry to eliminate rail joints by using a thermite weld system or weld to weld together two rail ends to form a smooth, continuous, and uninterrupted railroad rail. The thermite weld system is generally made by mounting a mold structure around the joint area of the two rail ends with an entry or gate on top for receiving molten weld material. The use of the thermite weld system is quite old and widespread in the railroad industry, and the system is time-consuming, labor-intensive, and hazardous to workers.
More specifically, to join two rail ends using the thermite weld system, the rails are laid and carefully aligned, leaving a small space between the ends. After alignment and leveling of the rail ends, the thermite weld system, which may include a three-piece mold preformed from a suitable refractory, such as bentonite and sand, is attached to the rail ends. One mold piece underlies both rail ends and two pieces extend upwardly from the lower piece on opposite sides of the rail ends. These mold pieces are securely clamped together and to the rails and extend over the top of the rails, leaving a gate at the top for the molten metal weld material to enter the mold. The mold may be arranged with upwardly extending risers coming off the shoe of the rails to allow trapped air and gases to escape when the molten metal weld material flows into the mold. A suitable material may be used to eliminate any spaces or gaps between the mold pieces and the rail surfaces.
As part of the welding process, the rail ends and surrounding portions of the rails are preheated by use of a propane torch or other suitable means to a red-hot condition of approximately 1800.degree. F. prior to pouring the molten weld material into the mold.
A crucible filled with a suitable powdered metal mixture is placed over the mold. The powdered metal mixture is ignited to transform the mixture into molten metal at approximately 4000.degree. to 5000.degree. F. The molten metal is then poured through the gate into the mold to fill the space between the rail ends and make the weld joint between the rail sections.
After waiting approximately five minutes, the weld joint has cooled enough to remove the malleable mold material from around the joint. However, the mold material remains dangerously hot. The crucible is removed, and then the clamps holding the mold material are carefully removed, leaving the hot mold material on the rails.
Heretofore, removing this mold material required two people. The first person would hold a shovel on the rail at one side of the mold, while the second person would slowly break off parts of the mold material with a sledge hammer. As the material was broken by the person handling the sledge, the material was caught in the shovel by the person handling the shovel. The use of the sledge hammer is dangerous because it can cause sparks to shoot out from the mold material and may further cause pieces of hot mold material to fly off of the rails. The person with the shovel then would carry the mold material which was still dangerously hot to a location where the ground was dry. If the broken mold material was accidentally dropped or placed in water or even in a wet location, a dangerous reaction or explosion could occur, and which in the past has caused severe injury. This dangerous process would be repeated until sufficient amounts of the mold material on the top of the rail, as well as on both sides of the rail, were removed.
A hydraulic shear would then be placed on the top of the rails to shear off the sprue left during the molding process. A grinder would next be used to smooth the weld at the ball of the rail. Although it was not necessary to remove the lower part of the mold material, some railroads would do so for the purpose of making the rail look neater. Any mold material left on the rail would eventually disintegrate in the weather.